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CVE-2026-48616 – Unauthenticated File Disclosure (IDOR) in Livechat – Rocket.Chat < 8.5.1 / 8.4.4…

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Summary

CVE-2026-48616 is a critical broken access control (IDOR) vulnerability in Rocket.Chat’s Livechat file download endpoint that allows any unauthenticated remote attacker to enumerate and download files uploaded across all rooms on an affected server. The flaw affects all Rocket.Chat releases below versions 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, 7.13.9, and 7.10.13, and carries a CVSS score of 9.3 (Critical).

Technical details

  • Root cause: The /file-upload/:fileId/:name endpoint authorizes Livechat access by validating a session triplet (rc_room_type=l, rc_rid, rc_token), but critically fails to verify that the supplied rc_rid actually corresponds to the room that owns the requested file. This is a classic Insecure Direct Object Reference (IDOR): an attacker can present a valid rc_rid from any Livechat session while requesting files belonging to an entirely different room, and the server will serve them without further checks.
  • Trigger conditions: An attacker obtains a minimal Livechat session token — for example by opening a public-facing Rocket.Chat Livechat widget — and uses that credential pair to request files from arbitrary rooms. No registered user account is required.
  • Attack vector: Fully remote and unauthenticated (AV:N/AC:L/PR:N/UI:N). File IDs (:fileId) are predictable sequential MongoDB ObjectIDs, enabling systematic enumeration of every file ever uploaded to the instance. The :name segment of the URL accepts any arbitrary value, removing a further potential barrier to exploitation.
  • Impact: Arbitrary cross-room file disclosure at scale (C:H). Livechat attachments routinely include sensitive material such as identity documents, PII-containing screenshots, and confidential support files. The CVSS Scope:Changed (S:C) metric reflects that the authorization boundary between chat rooms is violated, extending the impact well beyond the attacker’s own session context.

Affected software

  • Rocket.Chat < 8.5.1
  • Rocket.Chat < 8.4.4
  • Rocket.Chat < 8.3.6
  • Rocket.Chat < 8.2.6
  • Rocket.Chat < 8.1.6
  • Rocket.Chat < 8.0.7
  • Rocket.Chat < 7.13.9
  • Rocket.Chat < 7.10.13

Severity

CVSS 3.0 base score: 9.3 (Critical)
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Weakness: CWE-284 — Improper Access Control

Mitigation and recommended actions

  • Immediate — apply the vendor patch: Upgrade to the fixed release for your active version branch: 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, 7.13.9, or 7.10.13. The fix was delivered in GitHub PR #40889, which corrects the authorization logic in the file upload handler and Livechat room type processing.
  • If patching cannot be applied immediately: Restrict network-level access to the Rocket.Chat instance to trusted IP ranges, and consider temporarily disabling the Livechat feature to eliminate the exposed endpoint until a patch is applied.
  • Detection: Review server access logs for high-volume or sequential requests to /file-upload/ paths accompanied by Livechat session parameters (rc_room_type=l) originating from unknown or external IP addresses.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

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